<?php
/**
 * Smarty plugin
 *
 * This plugin is only for Smarty2 BC
 *
 * @package    Smarty
 * @subpackage PluginsFunction
 */

/**
 * Smarty {math} function plugin
 *
 * Type:     function<br>
 * Name:     math<br>
 * Purpose:  handle math computations in template
 *
 * @link     http://www.smarty.net/manual/en/language.function.math.php {math}
 *          (Smarty online manual)
 * @author   Monte Ohrt <monte at ohrt dot com>
 *
 * @param array                    $params   parameters
 * @param Smarty_Internal_Template $template template object
 *
 * @return string|null
 */
function smarty_function_math($params, $template) {
	static $_allowed_funcs = array(
			'int' => true,
			'abs' => true,
			'ceil' => true,
			'cos' => true,
			'exp' => true,
			'floor' => true,
			'log' => true,
			'log10' => true,
			'max' => true,
			'min' => true,
			'pi' => true,
			'pow' => true,
			'rand' => true,
			'round' => true,
			'sin' => true,
			'sqrt' => true,
			'srand' => true,
			'tan' => true
	);
	// be sure equation parameter is present
	if (empty($params['equation']))
	{
		trigger_error("math: missing equation parameter", E_USER_WARNING);

		return;
	}

	$equation = $params['equation'];

	// make sure parenthesis are balanced
	if (substr_count($equation, "(") != substr_count($equation, ")"))
	{
		trigger_error("math: unbalanced parenthesis", E_USER_WARNING);

		return;
	}

	// match all vars in equation, make sure all are passed
	preg_match_all("!(?:0x[a-fA-F0-9]+)|([a-zA-Z][a-zA-Z0-9_]*)!", $equation, $match);

	foreach ($match[1] as $curr_var)
	{
		if ($curr_var && !isset($params[$curr_var]) && !isset($_allowed_funcs[$curr_var]))
		{
			trigger_error("math: function call $curr_var not allowed", E_USER_WARNING);

			return;
		}
	}

	foreach ($params as $key => $val)
	{
		if ($key != "equation" && $key != "format" && $key != "assign")
		{
			// make sure value is not empty
			if (strlen($val) == 0)
			{
				trigger_error("math: parameter $key is empty", E_USER_WARNING);

				return;
			}
			if (!is_numeric($val))
			{
				trigger_error("math: parameter $key: is not numeric", E_USER_WARNING);

				return;
			}
			$equation = preg_replace("/\b$key\b/", " \$params['$key'] ", $equation);
		}
	}
	$smarty_math_result = null;
	eval("\$smarty_math_result = " . $equation . ";");

	if (empty($params['format']))
	{
		if (empty($params['assign']))
		{
			return $smarty_math_result;
		}
		else
		{
			$template->assign($params['assign'], $smarty_math_result);
		}
	}
	else
	{
		if (empty($params['assign']))
		{
			printf($params['format'], $smarty_math_result);
		}
		else
		{
			$template->assign($params['assign'], sprintf($params['format'], $smarty_math_result));
		}
	}
}

?>
